Add the INTERFACE_SYSTEM_INCLUDE_DIRECTORIES target property.

Unlike other target properties, this does not have a corresponding
non-INTERFACE variant.

This allows propagation of system attribute on include directories
from link dependents.

1 files changed, 4 insertions, 0 deletions

diff --git a/Tests/IncludeDirectories/SystemIncludeDirectories/upstream.cpp b/Tests/IncludeDirectories/SystemIncludeDirectories/upstream.cpp
new file mode 100644
index 0000000..f716b99
--- /dev/null
+++ b/Tests/IncludeDirectories/SystemIncludeDirectories/upstream.cpp
@@ -0,0 +1,4 @@
+
+#include "upstream.h"
+
+int upstream() { return systemlib(); }